Case-hardening of steel.



A. F. SHORE. CASE HARDENING OF STEEL.

APPLICATION FILED MAY 17, 1911.

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Application steam 17, 191i. sertii no. tamer.

To all whom may concern Be it known'that I, ALBERT F. SHORE, a

citizen of the United States, residing at 226 West Twenty-fourth street, New York, in the county of New York and State of New York, have invented certain new and useful Improvements in. Case-Hardening of 7 Steel,

of' which the following is a full, clear, and

exact specification.

This invention relates to a process of casehardening steel, and especiall such articles as armor-plate, gun projecti es, and large gear teeth, as well as parts of machinery subjected to such constant use and vibration that methods of case-hardening now known to the art have proved unreliab e, because of their inability to revent portions of the hardened surface rom flaking or peeling off; and the main object of the invention is to carburize a steel surface to such depths and in such a manner as to produce a relatively thick layer of carburized metal, which, when hardened, will remain permanently united with its softer backing under substantially all conditions of use.

I overcome the serious disadvantage just referred to by eliminating the flat cleavage plane between the hard and soft sections of the steel and providing instead an irregular cleavage surface between the two sections or strata of the steel, one such surface being formed by knob-like projections of the soft section extending upward a predetermined distance into the hard section, and thus providing an interlocking arrangement between the two sections, similar to plaster in wall lathing. This internal interlocking is due mainly to my process of carburization, the details of which will be set forth hereinafter, as well as other features of my invention, all of which are shown in the accompanying drawings forming part of this application, and in which drawings- Figure 1 illustrates the surface of a plate rotective coatings; Fig. 2 is a cross-section, illustrating the elfect of the coatings on the penetration of carbon and shows the condition of the surface section of the plate at the end of a first carburizing period, and Fig. 3 is a cross-section showing the extent of the carbon penetration after the removal of the coatings and at the end of a second carburizing period.

The drawings illustrate a specific embodiment of my invention, in which the first step in the proud employed is to protect certain portions of ."ie surface of the plate a 1, underneath which an irregular c1- wage surface is to be formed, from the carburizing agent, by suitable coverings, such as 2, which may be disk-like in form, of copper, enamel, cement, or the like, and of any deslred size or shape. In said process the plate 1 is then subjected to a first carburizing action by any suitable carburizing agent carburized to the desired depth as indicated in the carburized zone 3. The next step in said process is to remove the coverlngs 2, thus exposing the hitherto protected portions of the plate; after which the entire surface of the plate is then subjected to a second carburizing action, which is continued until the desired depth of carburization has been obtained, as indicated by the 1. The next step of said process is to thoroughly harden the plate by chilling, in any usual manner. By this recess an irregular cleavage surface wil be produced which will separate the hard and soft zones or sections of the plate and will outline interlocking means such as projections 5, fitting into corresponding sockets, for holding sai sections together in the form of a single unitary body. When a shell or projectile comes in contact with the surface of armorplate as heretofore made, the usual result is the shattering of the point or nose of the shell, while the hardened surface of the plate is simultaneously crushed and large flakes stripped from the surface of the plate in all directions, thus exposing the soft section thereof. The shell or projectile, havraaeaeea' se t. a, rare.

carburized none 3', Fig. 3, which is sectioned to distinguish it from the uncarburized zone ing an excess of penetrating energy, continues to cut into and through the soft section or back of the plate, punching out the same, as in a punching machine, and ex plodes in the interior of a vessel. The old type of armor-plate is thus seriously defective, in that the hardened section is detached from the soft section as above described; and frequently without warning large portions of the hardened section peel or flake ofi from the soft section of the plate because of internal stress resulting from heat treatment when the plate is made, and often augmented by extreme atmospheric changes.

According to my invention, it will beseen sults from the impact of s tiles,

inward t resistance alsoto the separation of the two zones and this prevents its detachment from the soft section-0f the late, which reells or projecor from other external orinternal causes. Thus fractures are not only localized, because of the irregular cleavage plane, but penetration of the plate b5 shells or projectiles is prevented, and the e struction or explosion of the latter on the exterior of the vessel is, assured Applied to machine parts, spotting with an atomizer may take the place of the disks Or coatings shown in Fig. 1, and here, as in the case of armor plates, thehardenin is produced by the carburizing and; chil ing methods above described; v p I It will be understood that various modifications" may be made in invention with g from the spirit and. scope out departi thereof. g

" What I claim-is:

1. Inafprocess of case-hardeningsteel, subjectin to direct shallow "carburiz'ation ofthe surface -of the f steel toi be treated, and subjecting to deepf carburization the re,

mainder of said surface.

2.1m a process of case-hardening steel,

subjecting" to direct shallow carburi'zation inward through the face thereof a 1n ulti-' plicity of relatively small areas of the surface of the Isteelto be'treatedyan'd subject ing to deepfcarburization the'remainder of said surface.

In a process of, case-hardening steel, subjecting to direct shallow carburization inward through the face thereof a multi-' plicity of relatively small areas of the surface of the steel to be treated, sub} cting t5 deep 'carburization the remainder of sai subjecting the surface and layer to rough the-face thereof portions p U ,7 H a 7. In a process of case-hardenin surface, andthen hardening the carburized layer so formed. 4 r

4. In a process of case-hardenin e carburized to carburization in two different stages in one of which portions of the surface,to be carburized are rotected from, and in the other of which tliey are exposed to, direct carburization.

5. In a process of case-hardenin steel, subj' cting' the surface and layer to, e carburized to two different carburizing actions during one of which portions of the surface tobe carburized are covered with carhon-resisting material and during the other of which said portions are not socovered. I

6. In a process of 'case-hardenin steel, covering portions of the surface of t carburizing 'the'j unprotectedfportions of said surface to the depth, removing th r rre i ng ma e i ls nd th n jectinglfthe entirefs'urfaceto ais'econd carburizing timer steel,

covering portions of the'surfa ce of t esteel to be treated with" disks of carbon-resisting material, carburizing thelmprotected portions of said surface tothe desired'depth,

removing the carbon-resisting material, and

then subjecting the entire surface to a second carburilzlng actionfor" the" desired length of'time. In testimony whereof, I aifix-my 7 signature, m presence of two w tnesses.

Y ALBERTF. SHORE, .Witnesses: I i

a na F. S ore,

steel,-

U esteel to be" ftreatedwith' carbon-resisting material,

action for desired length of 65 

